Guests arrive at Downton Abbey for a weekend house party which is to culminate in a performance by opera singer Dame Nellie Melba. Among them are Gregson, the eligible young Sir John Bullock, the widowed Duchess of Yeovil, and the handsome Viscount Gillingham, whom Mary hasn’t seen since childhood. Also present is Mr. Samson, a loose acquaintance from Robert’s gentleman’s club, and keen poker player. As Mary and Gillingham reminisce, a spark of friendship rekindles.
Downstairs, frenzied preparations for the weekend ahead leave an exasperated Mrs. Patmore strained. Gillingham’s valet, Green, tries to ingratiate himself with the staff, flattering Anna.
Over tea, Sir John Bullock devotes his attention to Lady Rose as they share their passion for jazz. Gillingham reveals to Mary that he’s currently single but is close to becoming engaged. Branson feels more than ever like a fish out of water in his uninspired small talk with the Duchess of Yeovil.
At dinner, Isobel confides in Dr. Clarkson her mixed feelings about attending Dame Melba’s concert, feeling disloyal to the memory of Matthew. Mary invites the guests to accompany her riding the following day and Gillingham is keen to oblige. Bates feels uneasy about the smooth-talking Green and warns Anna against him. The next day, Green regales the servants with news of Samson’s crushing defeat of Sir John Bullock at poker. He continues to flirt with Anna, much to Bates’ disapproval, but Anna that insists he is just trying to be nice. Molesley, humiliated, arrives with a box of groceries, admitting that he’s now a delivery man. Jimmy attempts to impress Ivy in front of his rival, Alfred, by opening a stuck jar but ends up spraining his wrist. Thomas is asked to step down as footman to take his place, but will have none of it.
While out riding, Gillingham describes his engagement to Mabel Lane Fox, a notable heiress, to Mary, hinting that the match is widely desired rather than passionate. He tells her that she’s lucky to have known great love with Matthew. Mary tells Gillingham about the estate’s tax bill and how Robert wants to sell land to settle it. Gillingham demonstrates real understanding, supporting her opposition to the plan and offering her advice.
That evening, Gregson confides that his plans for Germany are moving forward and tells Edith he hopes to win Robert’s approval. Another round of poker is planned, and Gregson offers to join. Mary is about to dance with Gillingham when she sees that the music is emanating from Matthew’s gramophone, which Rose had commandeered. Distraught, she retreats upstairs. Sampson again triumphs at the card table, this time with a great sum of Robert's – information that he shamefully hides from Cora. Mary sadly admits to Anna that she is not sure whether she is in mourning for Matthew or for her old self. Meanwhile, Edna, running into Branson, provides understanding and a sympathetic ear, and they reconnect.
The following day, Violet uncharacteristically reaches out to grieving Isobel, encouraging her to come to see Dame Melba sing. In typical snobbish fashion, Carson consigns her to eat dinner in her room, and distracted by his poker beating, Robert agrees. Short-staffed for the evening, Carson asks Molesley to stand in as footman, and Molesley reluctantly concedes that beggars can’t be choosers. Seizing his chance to impress Robert, Gregson tells Sampson he will try his luck with him again that evening.
Mrs. Patmore, stressed beyond her limits, suffers a panic attack, leaving Alfred to finish preparations. At the meal, Robert overcomes his snobbery of Dame Melba and Gillingham asks a noncommittal Mary out when she is next in London. After dinner Robert finds Branson alone and Branson tells him that he won’t ever be "one of them," but Robert won’t accept this. Branson, brooding and drunk, is at a crossroads.
After Dr. Clarkson has given Mrs Patmore the all-clear, the staff join the guests watching the concert. Anna leaves half way through to get a headache tablet from downstairs. She bumps into Green, whose attempted seduction quickly turns to violent rape. Meanwhile, Bates wonders why Anna is taking so long. After the concert Mrs Hughes finds Anna hiding, distraught and bloodied, in her office. Anna confides what has happened, but swears Mrs Hughes to secrecy, fearing that if Bates found out, he’d take revenge and end up back in prison.
Having exposed Sampson as a card sharp and beaten him at his own game, Gregson has won back other players’ losses. He returns Robert’s money and wins his respect. As night draws in, Edna steals into Branson’s bedroom to offer more fulsome consolation. Downstairs Anna has cleaned herself up before running into Bates. She claims to have fainted and ripped her dress, but Bates can tell she is hiding something. Unable to bear her vulnerability or his questions, Anna walks home alone.